Definition:
The geological time scale divides Earth’s history into intervals based
on major events in the rock and fossil record.
The four eons of Earth’s history. Source: Steven, E. (2015)
The eras (middle row) and periods (bottom row) of the Phanerozoic eon. Source: Steven, E. (2015)
The periods (middle row) and epochs (bottom row) of the Cenozoic era. Source: Steven, E. (2015)
Source: https://www.geologyin.com/
Source: https://www.geologyin.com/
A xenolith of diorite incorporated into a basalt lava flow, Mauna Kea volcano, Hawaii. The lava flow took place some time after the diorite cooled, was uplifted, and then eroded. (geological rock hammer head for scale). Source: Steven, E. (2015)
Superposition and cross-cutting relationships in Cretaceous Nanaimo Group rocks in Nanaimo, B.C. The coal seam is about 50 centimetres thick. The sequence of events is as follows: a) deposition of lower sandstone, b) faulting of lower sandstone, c) deposition of coal seam and d) deposition of upper sandstone. Source: Steven, E. (2015)
Source: https://geologybase.com/
The four types of unconformities: (a) a nonconformity between older non-sedimentary rock and sedimentary rock, (b) an angular unconformity, (c) a disconformity between layers of sedimentary rock, where the older rock has been eroded but not tilted, and (d) a paraconformity where there is a long period (typically millions of years) of non-deposition between two parallel layers. Source: Steven, E. (2015)
Source: https://earthsci.org
Source: https://divediscover.whoi.edu
